Bottom anti-reflective coatings (BARCs) have been widely used in conjunction with photo resists in the manufacture of semiconductors during the photolithography step of the process. The primary benefits of BARCs in photolithography are focus/exposure latitude improvement, enhanced critical dimension (CD) control, elimination of reflective notching, and protection of developable resist from substrate poisoning. In the past, BARCs have mainly been used in critical layers such as gate and contact layers. As integrated circuit feature sizes continue to shrink, the application of a BARC in implant layers becomes more desirable because the tolerances of reflective notching and CD variations caused by wafer topography are getting relatively smaller.
Developable BARCs (DBARCs) have been developed specifically for implant layer applications. The feasibility of using traditional dry-etch BARCs is very questionable because they introduce more process complexity and more defectivity and potentially cause unnecessary substrate damage.
A prior art method of dry patterning process using dry etch BARC's is shown in FIG. 1. In the dry patterning process, a BARC coating 102 is deposited on the substrate 101 or wafer, a resist coating 103 is applied over the BARC coating 102. The coated substrate is then selectively exposed to irradiation and undergoes a post-exposure bake. After the bake, an aqueous base development dissolves the exposed resist and a reactive ion etch removes the BARC coating underlying the removed resist. The area vacated by the resist and BARC is the subject to ion implantation.
A prior art method of wet-patterning process using DBARC is shown in FIG. 2. Similarly to the dry patterning process, a DBARC coating 202 is deposited on the substrate 201; a resist coating 203 is applied over the DBARC coating 202. The coated substrate is then selectively exposed to irradiation and undergoes a post-exposure bake. After the bake, an aqueous base development dissolves the exposed resist and unlike the dry patterning process dissolves the exposed DBARC coating as well.
While dry etch BARCS are used extensively for critical lithography layers requiring plasma pattern transfer, they typically cannot be used for implant layers for several reasons. First the etch process to clear the BARC is complex because controlling the etch end point is very difficult which makes the implant and diffusion process also difficult to control. Secondly, adjusting implant energies to penetrate appropriately through the remaining BARC layer is difficult. The BARC thickness may vary in relation to the local topography of the substrate or wafer. Lastly Ions used for the dry-etch step are highly energetic and may participate in the implant and diffusion process to decrease the efficiency of silicon performance.
Like any other BARC, DBARC is an organic liquid coating material used in conjunction with a photo resist during the photolithography step of the process to manufacture semiconductors. The difference between a DBARC and a dry-etch BARC in the lithographic process is that the DBARC is soluble in developer so it can be remove during the resist development step.
The advantages of using DBARC are also numerous. The number of process steps is reduced, substrate damage by plasma etching is eliminated, and thickness loss due to BARC etch is avoided. A major disadvantage to using DBARC is that it has limited resolution compared to dry-etch BARC because is very difficult to get a vertical pattern profile and reduce the standing wave. FIG. 3a is a representation of the photo acid distribution in the DBARC after heating. This distribution on and about the top surface of the photo acid 380 in the DBARC is a result of the anti-reflective properties of DBARC. A result of this distribution, a vertical profile of the side walls 305 is not effected after developing the DBARC coating as shown in FIG. 3b. 
It is thus an object of the present disclosure to obviate the disadvantage associated with the prior art and present a method to create a uniform vertical distribution of photo acid in the exposed DBARC layer by applying an electric field through the DBARC layer before or during the baking process.
It is also an object of the present disclosure to present a novel improvement for a method of making a semiconductor. The method including the steps of coating a substrate with a bottom anti-reflection coating; forming a resist film on the substrate over the anti reflection coating; selectively irradiating said resist film with light; after said irradiation, heating said resist film and applying an electric field to said resist film. The method also including the step of developing the resist film to remove selected portions of the resist film, where the developing step is performed subsequent to the electric field application. The novel improvement including using a developable bottom anti-reflection coating.
It is yet another object of the present disclosure to present a novel improvement for a method of making a semiconductor. The method including the steps of coating a substrate with a developable bottom anti-reflection coating, forming a resist film on the substrate over the anti reflection coating; selectively irradiating said resist film and developable bottom anti-reflection coating with light; and after irradiation, heating the resist film and developable bottom anti-reflection coating. The method also including developing the resist film and developable anti-reflection coating to remove selected portions of the resist film and selected portions of the developable anti-reflection coating. The novel improvement including applying an electric field to the developable anti-reflection coating after the step of irradiation and prior to the step of developing.
It is still another object of the present disclosure to present a novel method for patterning micro features by using a developable bottom anti-reflection coating. The method including the steps of diffusing the photo acid is one direction by a post exposure baking process and application of an electric field in the developable bottom anti-reflection coating layer.
It is also another object of the present disclosure to present a novel method to obtain a vertical distribution of photo acid in a selected portion of a developable bottom anti-reflective reflective coating layer. The method including selectively irradiating the developable bottom anti-reflection coating to form an area of concentrated photo acid on a portion of an upper surface of the developable bottom anti-reflection coating. The method also including, after irradiating, applying a vertical electric field normal to the upper s surface of the developable bottom anti reflection coating through the developable anti-reflection coating to diffuse the photo acid in a vertical direction.
These objects and other advantages of the disclosed subject matter will be readily apparent to one skilled in the art to which the disclosure pertains from a perusal or the claims, the appended drawings, and the following detailed description of the preferred embodiments.